Daybreak Health delivers mental health to teens; all our tech is there to support of literally putting a therapist in front of a K-through-12 student. Much more here: https://daybreakhealth.applytojob.com/apply/gJHzGLRsC4/Lead-...
Stack is React/Typescript on a Rails API backend, with pretty hefty support from Salesforce (as an electronic health record system).
Small company, small team, excellent culture - AMA! :)